On Mon, Oct 23, 2023 at 11:50:26PM -0400, Luben Tuikov wrote:
> Hi,
>
> On 2023-10-17 11:09, Matthew Brost wrote:
> > DRM_SCHED_POLICY_SINGLE_ENTITY creates a 1 to 1 relationship between
> > scheduler and entity. No priorities or run queue used in this mode.
> > Intended for devices with firmware schedulers.
> >
> > v2:
> > - Drop sched / rq union (Luben)
> > v3:
> > - Don't pick entity if stopped in drm_sched_select_entity (Danilo)
> > v4:
> > - Rework if statement in drm_sched_entity_init (Luben)
> > - Update comment for drm_sched_entity_to_scheduler (Luben)
> > - Reword a few things in DOC comment (Luben)
> > - Do not check sched policy in for statement (Luben)
> > v5:
> > - Fix extra blank lines (Luben / Checkpatch)
> >
> > Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/scheduler/sched_entity.c | 69 +++++++++++++++----
> > drivers/gpu/drm/scheduler/sched_fence.c | 2 +-
> > drivers/gpu/drm/scheduler/sched_main.c | 87 ++++++++++++++++++------
> > include/drm/gpu_scheduler.h | 8 +++
> > 4 files changed, 130 insertions(+), 36 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
> > index cf42e2265d64..940f63dd6965 100644
> > --- a/drivers/gpu/drm/scheduler/sched_entity.c
> > +++ b/drivers/gpu/drm/scheduler/sched_entity.c
> > @@ -83,6 +83,7 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
> > memset(entity, 0, sizeof(struct drm_sched_entity));
> > INIT_LIST_HEAD(&entity->list);
> > entity->rq = NULL;
> > + entity->single_sched = NULL;
> > entity->guilty = guilty;
> > entity->num_sched_list = num_sched_list;
> > entity->priority = priority;
> > @@ -90,8 +91,17 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
> > RCU_INIT_POINTER(entity->last_scheduled, NULL);
> > RB_CLEAR_NODE(&entity->rb_tree_node);
> >
> > - if(num_sched_list)
> > - entity->rq = &sched_list[0]->sched_rq[entity->priority];
> > + if (num_sched_list) {
> > + if (sched_list[0]->sched_policy !=
> > + DRM_SCHED_POLICY_SINGLE_ENTITY) {
> > + entity->rq = &sched_list[0]->sched_rq[entity->priority];
> > + } else if (num_sched_list == 1 && !sched_list[0]->single_entity) {
> > + sched_list[0]->single_entity = entity;
> > + entity->single_sched = sched_list[0];
>
> To simplify the rest of the GPU scheduler design and generalize the logic,
> we can do
> entity->rq = sched_list[0]->sched_rq[entity->priority];
> where the "priority" is 0, thus having a single rq.
>
> We shouldn't splice scheduler and entity, but rather make it so that
> we can set the number of rqs to 1, thus resulting in a single rq.
>
> (https://lore.kernel.org/r/20231023032251.164775-1-luben.tuikov@xxxxxxx)
>
I pulled out this patch [1] + previous one [2] and included your [3] to
test this in Xe [4].
It seems to work with just one rq per scheduler. We can go with this
approach in feel like this is the route. My next post will include your
patch [3] if we agree.
Matt
[1] https://patchwork.freedesktop.org/patch/563094/?series=121745&rev=8
[2] https://patchwork.freedesktop.org/patch/563093/?series=121745&rev=8
[3] https://patchwork.freedesktop.org/patch/563817/?series=125433&rev=1
[4] https://patchwork.freedesktop.org/series/125540/
> > + } else {
> > + return -EINVAL;
> > + }
> > + }
> >
> > init_completion(&entity->entity_idle);
> >
> > @@ -124,7 +134,8 @@ void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
> > struct drm_gpu_scheduler **sched_list,
> > unsigned int num_sched_list)
> > {
> > - WARN_ON(!num_sched_list || !sched_list);
> > + WARN_ON(!num_sched_list || !sched_list ||
> > + !!entity->single_sched);
>
> We wouldn't need this check.
>
> >
> > entity->sched_list = sched_list;
> > entity->num_sched_list = num_sched_list;
> > @@ -231,13 +242,15 @@ static void drm_sched_entity_kill(struct drm_sched_entity *entity)
> > {
> > struct drm_sched_job *job;
> > struct dma_fence *prev;
> > + bool single_entity = !!entity->single_sched;
> >
> > - if (!entity->rq)
> > + if (!entity->rq && !single_entity)
> > return;
> >
> > spin_lock(&entity->rq_lock);
> > entity->stopped = true;
> > - drm_sched_rq_remove_entity(entity->rq, entity);
> > + if (!single_entity)
> > + drm_sched_rq_remove_entity(entity->rq, entity);
> > spin_unlock(&entity->rq_lock);
>
> We should be able to carry on the existing infrastructure when
> having num_rqs = 1, with dynamic rqs. So we shouldn't warrant
> any changes here.
>
> >
> > /* Make sure this entity is not used by the scheduler at the moment */
> > @@ -259,6 +272,20 @@ static void drm_sched_entity_kill(struct drm_sched_entity *entity)
> > dma_fence_put(prev);
> > }
> >
> > +/**
> > + * drm_sched_entity_to_scheduler - Schedule entity to GPU scheduler
> > + * @entity: scheduler entity
> > + *
> > + * Returns GPU scheduler for the entity
> > + */
> > +struct drm_gpu_scheduler *
> > +drm_sched_entity_to_scheduler(struct drm_sched_entity *entity)
> > +{
> > + bool single_entity = !!entity->single_sched;
> > +
> > + return single_entity ? entity->single_sched : entity->rq->sched;
>
> It would be "entity->rq->sched" for any and all cases which simplifies things.
>
> > +}
> > +
> > /**
> > * drm_sched_entity_flush - Flush a context entity
> > *
> > @@ -276,11 +303,12 @@ long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
> > struct drm_gpu_scheduler *sched;
> > struct task_struct *last_user;
> > long ret = timeout;
> > + bool single_entity = !!entity->single_sched;
> >
> > - if (!entity->rq)
> > + if (!entity->rq && !single_entity)
> > return 0;
> >
> > - sched = entity->rq->sched;
> > + sched = drm_sched_entity_to_scheduler(entity);
> > /**
> > * The client will not queue more IBs during this fini, consume existing
> > * queued IBs or discard them on SIGKILL
> > @@ -373,7 +401,7 @@ static void drm_sched_entity_wakeup(struct dma_fence *f,
> > container_of(cb, struct drm_sched_entity, cb);
> >
> > drm_sched_entity_clear_dep(f, cb);
> > - drm_sched_wakeup_if_can_queue(entity->rq->sched);
> > + drm_sched_wakeup_if_can_queue(drm_sched_entity_to_scheduler(entity));
> > }
>
> We can carry on that too, without changes. The good part of that is that
> we'll inherit all the fence work and checking for free.
>
> >
> > /**
> > @@ -387,6 +415,8 @@ static void drm_sched_entity_wakeup(struct dma_fence *f,
> > void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
> > enum drm_sched_priority priority)
> > {
> > + WARN_ON(!!entity->single_sched);
> > +
> > spin_lock(&entity->rq_lock);
> > entity->priority = priority;
> > spin_unlock(&entity->rq_lock);
> > @@ -399,7 +429,7 @@ EXPORT_SYMBOL(drm_sched_entity_set_priority);
> > */
> > static bool drm_sched_entity_add_dependency_cb(struct drm_sched_entity *entity)
> > {
> > - struct drm_gpu_scheduler *sched = entity->rq->sched;
> > + struct drm_gpu_scheduler *sched = drm_sched_entity_to_scheduler(entity);
> > struct dma_fence *fence = entity->dependency;
> > struct drm_sched_fence *s_fence;
> >
> > @@ -501,7 +531,8 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
> > * Update the entity's location in the min heap according to
> > * the timestamp of the next job, if any.
> > */
> > - if (entity->rq->sched->sched_policy == DRM_SCHED_POLICY_FIFO) {
> > + if (drm_sched_entity_to_scheduler(entity)->sched_policy ==
> > + DRM_SCHED_POLICY_FIFO) {
> > struct drm_sched_job *next;
> >
> > next = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));
> > @@ -524,6 +555,8 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
> > struct drm_gpu_scheduler *sched;
> > struct drm_sched_rq *rq;
> >
> > + WARN_ON(!!entity->single_sched);
> > +
> > /* single possible engine and already selected */
> > if (!entity->sched_list)
> > return;
> > @@ -573,12 +606,13 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
> > void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
> > {
> > struct drm_sched_entity *entity = sched_job->entity;
> > - bool first, fifo = entity->rq->sched->sched_policy ==
> > - DRM_SCHED_POLICY_FIFO;
> > + bool single_entity = !!entity->single_sched;
> > + bool first;
> > ktime_t submit_ts;
> >
> > trace_drm_sched_job(sched_job, entity);
> > - atomic_inc(entity->rq->sched->score);
> > + if (!single_entity)
> > + atomic_inc(entity->rq->sched->score);
> > WRITE_ONCE(entity->last_user, current->group_leader);
> >
> > /*
> > @@ -591,6 +625,10 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
> >
> > /* first job wakes up scheduler */
> > if (first) {
> > + struct drm_gpu_scheduler *sched =
> > + drm_sched_entity_to_scheduler(entity);
> > + bool fifo = sched->sched_policy == DRM_SCHED_POLICY_FIFO;
> > +
> > /* Add the entity to the run queue */
> > spin_lock(&entity->rq_lock);
> > if (entity->stopped) {
> > @@ -600,13 +638,14 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
> > return;
> > }
> >
> > - drm_sched_rq_add_entity(entity->rq, entity);
> > + if (!single_entity)
> > + drm_sched_rq_add_entity(entity->rq, entity);
> > spin_unlock(&entity->rq_lock);
> >
> > if (fifo)
> > drm_sched_rq_update_fifo(entity, submit_ts);
> >
> > - drm_sched_wakeup_if_can_queue(entity->rq->sched);
> > + drm_sched_wakeup_if_can_queue(sched);
> > }
> > }
> > EXPORT_SYMBOL(drm_sched_entity_push_job);
> > diff --git a/drivers/gpu/drm/scheduler/sched_fence.c b/drivers/gpu/drm/scheduler/sched_fence.c
> > index 06cedfe4b486..f6b926f5e188 100644
> > --- a/drivers/gpu/drm/scheduler/sched_fence.c
> > +++ b/drivers/gpu/drm/scheduler/sched_fence.c
> > @@ -225,7 +225,7 @@ void drm_sched_fence_init(struct drm_sched_fence *fence,
> > {
> > unsigned seq;
> >
> > - fence->sched = entity->rq->sched;
> > + fence->sched = drm_sched_entity_to_scheduler(entity);
> > seq = atomic_inc_return(&entity->fence_seq);
> > dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled,
> > &fence->lock, entity->fence_context, seq);
> > diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> > index 150e5330f0fa..273e0fbc4eab 100644
> > --- a/drivers/gpu/drm/scheduler/sched_main.c
> > +++ b/drivers/gpu/drm/scheduler/sched_main.c
> > @@ -32,7 +32,8 @@
> > * backend operations to the scheduler like submitting a job to hardware run queue,
> > * returning the dependencies of a job etc.
> > *
> > - * The organisation of the scheduler is the following:
> > + * For scheduling policies DRM_SCHED_POLICY_RR and DRM_SCHED_POLICY_FIFO, the
> > + * scheduler organization is:
> > *
> > * 1. Each hw run queue has one scheduler
> > * 2. Each scheduler has multiple run queues with different priorities
> > @@ -43,7 +44,24 @@
> > *
> > * The jobs in a entity are always scheduled in the order that they were pushed.
> > *
> > - * Note that once a job was taken from the entities queue and pushed to the
> > + * For DRM_SCHED_POLICY_SINGLE_ENTITY, the organization of the scheduler is:
> > + *
> > + * 1. One to one relationship between scheduler and entity
> > + * 2. No priorities implemented per scheduler (single job queue)
> > + * 3. No run queues in scheduler rather jobs are directly dequeued from entity
> > + * 4. The entity maintains a queue of jobs that will be scheduled to the
> > + * hardware
> > + *
> > + * The jobs in a entity are always scheduled in the order that they were pushed
> > + * regardless of scheduling policy. Single-entity scheduling is essentially a
> > + * FIFO for jobs.
> > + *
> > + * A policy of DRM_SCHED_POLICY_RR or DRM_SCHED_POLICY_FIFO is expected to be
> > + * used when the kernel-mode driver is scheduling directly to the hardware while
> > + * a scheduling policy of DRM_SCHED_POLICY_SINGLE_ENTITY is expected to be used
> > + * when there is a firmware scheduler.
> > + *
> > + * Note that once a job is taken from the entities queue and pushed to the
> > * hardware, i.e. the pending queue, the entity must not be referenced anymore
> > * through the jobs entity pointer.
> > */
> > @@ -96,6 +114,8 @@ static inline void drm_sched_rq_remove_fifo_locked(struct drm_sched_entity *enti
> >
> > void drm_sched_rq_update_fifo(struct drm_sched_entity *entity, ktime_t ts)
> > {
> > + WARN_ON(!!entity->single_sched);
> > +
> > /*
> > * Both locks need to be grabbed, one to protect from entity->rq change
> > * for entity from within concurrent drm_sched_entity_select_rq and the
> > @@ -126,6 +146,8 @@ void drm_sched_rq_update_fifo(struct drm_sched_entity *entity, ktime_t ts)
> > static void drm_sched_rq_init(struct drm_gpu_scheduler *sched,
> > struct drm_sched_rq *rq)
> > {
> > + WARN_ON(sched->sched_policy == DRM_SCHED_POLICY_SINGLE_ENTITY);
> > +
> > spin_lock_init(&rq->lock);
> > INIT_LIST_HEAD(&rq->entities);
> > rq->rb_tree_root = RB_ROOT_CACHED;
> > @@ -144,6 +166,8 @@ static void drm_sched_rq_init(struct drm_gpu_scheduler *sched,
> > void drm_sched_rq_add_entity(struct drm_sched_rq *rq,
> > struct drm_sched_entity *entity)
> > {
> > + WARN_ON(!!entity->single_sched);
> > +
> > if (!list_empty(&entity->list))
> > return;
> >
> > @@ -166,6 +190,8 @@ void drm_sched_rq_add_entity(struct drm_sched_rq *rq,
> > void drm_sched_rq_remove_entity(struct drm_sched_rq *rq,
> > struct drm_sched_entity *entity)
> > {
> > + WARN_ON(!!entity->single_sched);
> > +
> > if (list_empty(&entity->list))
> > return;
> >
> > @@ -641,7 +667,7 @@ int drm_sched_job_init(struct drm_sched_job *job,
> > struct drm_sched_entity *entity,
> > void *owner)
> > {
> > - if (!entity->rq)
> > + if (!entity->rq && !entity->single_sched)
> > return -ENOENT;
> >
> > job->entity = entity;
> > @@ -674,13 +700,16 @@ void drm_sched_job_arm(struct drm_sched_job *job)
> > {
> > struct drm_gpu_scheduler *sched;
> > struct drm_sched_entity *entity = job->entity;
> > + bool single_entity = !!entity->single_sched;
> >
> > BUG_ON(!entity);
> > - drm_sched_entity_select_rq(entity);
> > - sched = entity->rq->sched;
> > + if (!single_entity)
> > + drm_sched_entity_select_rq(entity);
> > + sched = drm_sched_entity_to_scheduler(entity);
> >
> > job->sched = sched;
> > - job->s_priority = entity->rq - sched->sched_rq;
> > + if (!single_entity)
> > + job->s_priority = entity->rq - sched->sched_rq;
> > job->id = atomic64_inc_return(&sched->job_id_count);
> >
> > drm_sched_fence_init(job->s_fence, job->entity);
> > @@ -896,6 +925,14 @@ drm_sched_select_entity(struct drm_gpu_scheduler *sched)
> > if (!drm_sched_can_queue(sched))
> > return NULL;
> >
> > + if (sched->single_entity) {
> > + if (!READ_ONCE(sched->single_entity->stopped) &&
> > + drm_sched_entity_is_ready(sched->single_entity))
> > + return sched->single_entity;
> > +
> > + return NULL;
> > + }
> > +
> > /* Kernel run queue has higher priority than normal run queue*/
> > for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
> > entity = sched->sched_policy == DRM_SCHED_POLICY_FIFO ?
> > @@ -1092,6 +1129,7 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
> > return -EINVAL;
> >
> > sched->ops = ops;
> > + sched->single_entity = NULL;
> > sched->hw_submission_limit = hw_submission;
> > sched->name = name;
> > if (submit_wq) {
> > @@ -1111,8 +1149,10 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
> > sched->dev = dev;
> > sched->sched_policy = sched_policy == DRM_SCHED_POLICY_UNSET ?
> > drm_sched_policy_default : sched_policy;
> > - for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_COUNT; i++)
> > - drm_sched_rq_init(sched, &sched->sched_rq[i]);
> > + if (sched_policy != DRM_SCHED_POLICY_SINGLE_ENTITY) {
> > + for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_COUNT; i++)
> > + drm_sched_rq_init(sched, &sched->sched_rq[i]);
> > + }
>
> With dynamic rq, no changes would be necessary here--we just go over the single rq.
>
> >
> > init_waitqueue_head(&sched->job_scheduled);
> > INIT_LIST_HEAD(&sched->pending_list);
> > @@ -1143,19 +1183,24 @@ void drm_sched_fini(struct drm_gpu_scheduler *sched)
> >
> > drm_sched_wqueue_stop(sched);
> >
> > - for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
> > - struct drm_sched_rq *rq = &sched->sched_rq[i];
> > -
> > - spin_lock(&rq->lock);
> > - list_for_each_entry(s_entity, &rq->entities, list)
> > - /*
> > - * Prevents reinsertion and marks job_queue as idle,
> > - * it will removed from rq in drm_sched_entity_fini
> > - * eventually
> > - */
> > - s_entity->stopped = true;
> > - spin_unlock(&rq->lock);
> > + if (sched->single_entity) {
> > + spin_lock(&sched->single_entity->rq_lock);
> > + sched->single_entity->stopped = true;
> > + spin_unlock(&sched->single_entity->rq_lock);
> > + } else if (sched->sched_policy != DRM_SCHED_POLICY_SINGLE_ENTITY) {
> > + for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
> > + struct drm_sched_rq *rq = &sched->sched_rq[i];
> >
> > + spin_lock(&rq->lock);
> > + list_for_each_entry(s_entity, &rq->entities, list)
> > + /*
> > + * Prevents reinsertion and marks job_queue as idle,
> > + * it will removed from rq in drm_sched_entity_fini
> > + * eventually
> > + */
> > + s_entity->stopped = true;
> > + spin_unlock(&rq->lock);
> > + }
> > }
>
> Same here--we can keep the loop intact, we have a single rq and we just process it.
>
> >
> > /* Wakeup everyone stuck in drm_sched_entity_flush for this scheduler */
> > @@ -1186,6 +1231,8 @@ void drm_sched_increase_karma(struct drm_sched_job *bad)
> > struct drm_sched_entity *entity;
> > struct drm_gpu_scheduler *sched = bad->sched;
> >
> > + WARN_ON(sched->sched_policy == DRM_SCHED_POLICY_SINGLE_ENTITY);
> > +
> > /* don't change @bad's karma if it's from KERNEL RQ,
> > * because sometimes GPU hang would cause kernel jobs (like VM updating jobs)
> > * corrupt but keep in mind that kernel jobs always considered good.
> > diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
> > index 320f0a720486..e67b53c3546b 100644
> > --- a/include/drm/gpu_scheduler.h
> > +++ b/include/drm/gpu_scheduler.h
> > @@ -79,6 +79,7 @@ enum drm_sched_policy {
> > DRM_SCHED_POLICY_UNSET,
> > DRM_SCHED_POLICY_RR,
> > DRM_SCHED_POLICY_FIFO,
> > + DRM_SCHED_POLICY_SINGLE_ENTITY,
> > DRM_SCHED_POLICY_COUNT,
> > };
> >
> > @@ -112,6 +113,9 @@ struct drm_sched_entity {
> > */
> > struct drm_sched_rq *rq;
> >
> > + /** @single_sched: Single scheduler */
> > + struct drm_gpu_scheduler *single_sched;
> > +
> > /**
> > * @sched_list:
> > *
> > @@ -473,6 +477,7 @@ struct drm_sched_backend_ops {
> > * struct drm_gpu_scheduler - scheduler instance-specific data
> > *
> > * @ops: backend operations provided by the driver.
> > + * @single_entity: Single entity for the scheduler
> > * @hw_submission_limit: the max size of the hardware queue.
> > * @timeout: the time after which a job is removed from the scheduler.
> > * @name: name of the ring for which this scheduler is being used.
> > @@ -504,6 +509,7 @@ struct drm_sched_backend_ops {
> > */
> > struct drm_gpu_scheduler {
> > const struct drm_sched_backend_ops *ops;
> > + struct drm_sched_entity *single_entity;
>
> Right, as I mentioned above, we shouldn't splice up between a scheduler
> and an entity sometimes, and other times scheduler to rq to entity--it just
> creates too much thrashing about in the code, with too many ifs, conditions,
> etc. Simpler is better--parameterization of the number of rqs.
>
> Instead, let's get the dynamic rqs in, and this way we can keep much
> of the code the same, inheriting fence work and checks, and so on,
> without much changes.
>
> Regards,
> Luben
>
> > uint32_t hw_submission_limit;
> > long timeout;
> > const char *name;
> > @@ -587,6 +593,8 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
> > struct drm_gpu_scheduler **sched_list,
> > unsigned int num_sched_list,
> > atomic_t *guilty);
> > +struct drm_gpu_scheduler *
> > +drm_sched_entity_to_scheduler(struct drm_sched_entity *entity);
> > long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout);
> > void drm_sched_entity_fini(struct drm_sched_entity *entity);
> > void drm_sched_entity_destroy(struct drm_sched_entity *entity);
>
